The Mysterious Traveler was a mystery drama anthololgy which ran for nine years (1943-1952). Each week listeners were invited to ride a passenger train in the company of a mysterious stranger (Maurice Tarplin), who always had a dark and uncanny tale for a willing ear. Created by the writing team of Robert A. Arthur and David Kogan, the series was popular enough to engender two 'spin-off' series—The Sealed Book and The Strange Dr. Weird.
Both spin-offs produced no originals, only remakes of MT stories (along with some remakes of Dark Destiny). The Sealed Book tended to deal with murder as its primary subject, while The Strange Dr. Weird (also hosted by Tarplin) leaned more toward the macabre. The Mysterious Traveler boasted nearly 400 episodes of which, sadly, only about 71 have survived. That being the case, I have decided only to list the shows known to still exist.
Synopsis used from: http://www.otrplotspot.com/mysteriousTraveler.html